This strange device looks like a metal tube that has been kneaded by external forces. When you put it around the ear, you can hear a series of low, dangerous ticks. This device was called "Opticus" in the era of ancient civilization. No one can understand the true meaning of the name, just as no one can accurately predict its effect. In reality, its effect was decided before each Opticus was made, not even its manufacturer can make any alteration or optimization to it. This may sound ridiculous, but it is the fact!